Core barrel assemblies are used in a variety of drilling industries such as in the fields of ore mining, petroleum drilling, water well drilling, and geotechnical drilling and surveying industries. Core barrel assemblies are used to obtain a core sample at an end of a drilling passage. Typical core barrel assemblies include an inner tube assembly and an outer tube assembly. The outer tube assembly contains the inner tube assembly and provides engagement to other drilling components such as a drill string or collection of drill rods.
During a core sampling operation, after collecting a core sample from a bottom region of a drill hole, the inner tube assembly contains the core sample. The inner tube and core sample are retrieved from the bottom of the drill hole using a wire line that is pulled through the drill rods.
Depending upon the configuration of the core barrel assembly and/or the inner tube, a variety of components may be engaged with the inner tube such as a core barrel head and a core lifter. These components and potentially others are engaged with the inner tube by threaded connections. These threaded connections must be disengaged from one another in order to remove the core sample.
Engaging or disengaging threaded components with an inner tube such as in accessing a core sample contained in the inner tube, can be problematic. Relatively high levels of torque may be required. Dirt and debris may cover the components and/or threads. Exposure and contact with core drilling fluids may pose additional problems. Bentonite clay drilling fluids contain clay particles and can be slightly corrosive. Drilling fluids may also include polymer filtration control and stabilizers, lubricants such as drill rod grease, and cutting oils. The presence of these agents on the inner tube and/or threaded regions, can further impede engagement or disengagement operations particularly in situations when the outer surface of the tube contains lubricious agents.
Core barrel assemblies are typically machined assemblies with relatively high tolerances. Thus, it is important to not damage the outer surface of the inner tube such as by using a traditional pipe wrench. Typical pipe wrenches have pipe engaging faces with teeth that can form “digs,” burrs, or other surface defects on the outer surface of the inner tube. In addition, if excessive force is applied by a pipe wrench, the inner tube can be deformed.
In view of these and other reasons, the drilling industry typically uses specialized wrenches with a carbide coating to grip core barrel assemblies and particularly inner tubes. Although satisfactory in certain aspects, a need remains for an improved tool for securely engaging core barrel components such as an inner tube, without damaging the component.